1. Field of the Invention
This invention relates to the field of propellant gas delivery systems. More specifically, the invention comprises an improved energy delivery cartridge with a burst cup that allows controlled discharge of the propellant gases generated within said cartridge. The invention further comprises a method for forming said improved energy delivery cartridge during an assembly process.
2. Description of the Related Art
Although the present invention can be applied to any application requiring the use of metered propellant gases, it was primarily developed as part of a propellant system for launching 40 mm grenades (such as the U.S. Army's M433). The invention is an improvement to a prior design reduced to practice by the same inventor. The prior design is disclosed and claimed in U.S. Pat. No. 7,004,074 to Van Stratum (2006), which is hereby expressly incorporated by reference.
Metallic cartridges have been used to encapsulate solid propellants for many years. In recent years other materials have been substituted for the traditional brass, but the principles of operation remain the same: A projectile is seated in the open mouth of a cartridge case containing solid propellant. Ignition of the propellant is provided by percussive or electrical means. The burning propellant generates pressurized gas which forces the projectile out of the mouth of the case and then typically through a barrel bore.
The launching of a 40 mm grenade involves the same principles. The main difference, however, is the size and mass of the projectile. A typical shoulder-fired military weapon launches a projectile weighing less than 30 grams at a relatively high velocity (700-1,000 meters per second). In contrast, a 40 mm grenade weapon launches a projectile weighing over 200 grams at a relatively low velocity (70-80 meters per second). Thus, while the operating principles between the two types of weapons are the same, they can be said to operate in different regimes.
Since the human operator can only withstand a fixed amount of recoil, one cannot merely scale up the cartridge of a shoulder-fired rifle and create a useable weapon for launching 40 mm grenades. The design considerations are different. The incorporated U.S. Pat. No. 7,004,074 illustrates and describes an effective approach to the problem of launching large masses at low velocities. The '074 invention uses a high-pressure cartridge embedded within a low-pressure larger cartridge. A burst cup metering system is used to meter propellant gases from the high pressure cartridge into the low pressure cartridge, thereby accelerating the projectile in a smooth and controlled fashion. This approach helps to reduce the peak recoil loads experienced by a user. The high pressure found within the high pressure cartridge also ensures the reliable ignition and combustion of the propellant it contains.
The present invention seeks to simplify the construction and assembly of a suitable High-Low gas pressure cartridge. Although the illustrations and descriptions pertain to 40 mm grenade launchers, the reader should bear in mind that the invention applies to many fields beyond military munitions. A good example is disclosed in U.S. Pat. No. 6,189,926 to Smith (2001), which uses a High-Low pressure cartridge to inflate an airbag. Additional applications would include, without limitation:
1. Turbine and piston engine starters;
2. Parachute inflation devices;
3. Mechanical deployment device;
4. Life vest inflation devices;
5. Life boat inflation devices; and
6. Explosive bolt cutting devices.